1. Field of the Invention
The present invention is a video multiplexer. In particular, it is for a video multiplexer suitable for scoring systems of events, such as bomb scoring systems.
2. Description of the Prior Art
Previously video signals have been combined by a split screen technique where two or more separate images each share a portion of a composite video image. These composite images are created by selectively imposing portions of one image transmission raster on another transmission raster to provide for one master image. This is commonly seen in commercial television with video displays of people side by side who are separated by significant distances.
To superimpose a third raster in real time, a second machine is necessary to impose the third on the composition of the first two. Thus, each additional image requires additional apparatus to superimpose the next transmission raster. Each time such a combination occurs there is a loss of image quality. The initial two transmission rasters for several repetitions may lose the horizontal sync of the first rasters. If this occurs, the overall video image is lost.
CMOS and TTL are ways for identifying standard electrical components. CMOS stands for combination metallic oxide semiconductor and TTL stands for transistor-transistor logic. TTL and CMOS each have unique levels of voltage to drive those types of circuit components. Programmable read only memory, PROM, and erasable programmable read only memory, EPROM, are standard off the shelf memory devices. In choosing such memory devices, the desire is to have the amount of capacity necessary to do a given function. Standard CMOS components come in 4000 series which is an industry standard of notation and TTL devices come in standard 7400 series which is also a standard industry notation. This permits comparable components to be purchased from different manufactures.